Improvement in balanced valves



l. A. HUTCHISUN.

Balanced-Valvm N0.1O,327. Patented Marh2,.1875.l

UNITED STATES PATENT GEEIG'..

JAMES A. HUTCHISON, OF PITTSBURG, PENNSYLVANIA.

IMPRVEMENT IN BALANCED VALVES.

Specification forming part of Letters Patent No. 160,327, dated March 2,1875; application tiled January 9, 1875.

To all whom it may concern:

Beit known that I, J AMES A. HUTcHIsoN, of Pittsburg, county ofAllegheny, State of Pennsylvania, have invented or discovered a new anduseful Improvement in Steam-Engine Balanced Valves; and I do herebydeclare the following to be a full, clear, concise, and exactdescription thereof, reference being had to the accompanying drawing'making a part of this specification, in which-like letters indicatinglike parts- Figure l is a longitudinal sectional view of a steam-valvechest, with my improved valve construction arranged therein. Fig. 2 is atransverse section through a: x, Fig. 1, and

Fig. 3, by a diagram, illustrates the relative areas of the steam pipeand ports.

The object of my invention is, first, an improved construction ofbalanced valve; second, an arrangement of ports in connection with theordinary steam-chest and steam-cylinder, whereby the steamexhaust portswill exceed in capacity the steam-receiving ports.

In the drawing, B represents an ordinary steam-chest, and a a thesteam-ports, leading to the opposite ends of the cylinder, and b theexhaust-port. Inside the steam-chest B I arrange a valve-case, D, ofcylindrical or other suitable form, as square, rectangular, orotherwise, in cross-section, and in this I arrange the piston-valves dd1 d2, of any suitable construction, and affix them to a common valvestem, d3. rEhe ends of the valve-ease D are always open, at least tosuch extent as to allow the steam-pressure to act against the outer endsof the outer piston-valves d d2, so that so far as relates tolongitudinal pressure these piston-valves will be perfectly balanced,and also when steam is admitted between d and d1, or d1 and d2, suchpressure acting equally either way,wi1l not destroy such balance. Atsuitable .points in the opposite sides of the valve-case D, and oppositeeach other, I make the steam-supply ports e so that when a piston-valve,d or d2, is passing such ports the steam-pressure, acting equally on itsopposite sides, will leave it, as to lateral pressure, perfectlybalanced. These ports e, at the opposite ends of the valve-case D, arealternately covered and uncovered by the end piston- Valves d d2, so asthereby to open and cut oif communication alternately to and from thesteam-receiving ports c a', which lead to the opposite ends of themain-cylinder, and the middle piston-valve d1 passes back and forth overthe exhaust-port b, so as to open and close the exhaust, as will bereadily understood by those skilled in the art. Steam is supplied fromthe boiler by the usual pipe, f.

By arranging now the relative areas of these ports I am enabled moreperfectly than has, I believe, been done by any like means to secure,with any given or desired steam-receiving capacity, a greatersteam-exhaust capacity, and to this end I make the area `incross-section of each of the ports a a b greater than the aggregate areaof each pair of supply-ports e c, (the two ports opposite each otherbeing cousideredas a pair.) While not limiting myself to any specific orfixed relative area for such ports and for the steam-pipe f, I haveillustrated in the diagram, Fig. 3, what I believe to be the bestrelative areas. In this diagram, supposing the area in cross-section ofthe pipe f to be l, the area of two opposite ports c c is represented asl, and of each of theiports a a bis represented approximately as 2.Hence the steam-exhausting capacity ot' the engine on either stroke fromone end of the main cylinder will be double, or about double, thesteam-receiving capacity, on the same stroke, to the other end of themain cylinder.

By thus rapidly exhausting the steam in the manner described I get rid,in part at least, of the difculty experienced from the presence ofexhaust-steam in the cylinder as a hindrance to the forward stroke. But,as already stated, the relative areas of these ports may be varied,provided only that each port a a b shall have an area greater than thatof each pair of ports c c; and for the purposes of this part of myinvention a single supply-port of the same area may take the place ofeach pair of ports e c.

In order that the piston-valves d d1 d2 may, under the equal or balancedpressure to which they are subject at all times, as above set forth,work with perfect freedom, and without binding at all from imperfectalignment, or from an imperfect adjustment of the packing, I connect thevalve-stem m to the pistonvalves by a hook, m', engaging an eye, n,which latter, as affixed to the piston-valves or their stem, though inlieu thereof other suitable joint may be used, as a ball-and-sockct,swivel, hinge, or other like joint.

The result above stated will thus be secured, and the piston-valves eldl d2 being ground or provided with any suitable means of self-packing,Will Work free andtrue in their case D.

What I claim as my invention, and desire to secure by Letters Patent, is

l. The piston-valves d d1 d2 and the valvecase D, in which they operate,arranged in the steam-chest B, the interposed valve d1 serving to governthe exhaust-port, whereby steampressure being free to act against theouter ends of the outer piston-valves, and in the operation of theengine, between the valves, such my hand.

JAMES A. HUTCHISON.

Witnesses: W. GIBSON MILLER, LEWIS HUTGHIsoN.

